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ANNE JACOBUS MATHIJS AUGUST RIDDER VAN DER DOES m5 Bus.

FURNACE.

2 SHEETS-SHEET I- Patented Aug. 26, 1919.

OOIDO APPLICATION FILED JUNE 6. I918 o o o o o o o o o o o 0 0 /N VE/V TOR w w 5 M w M N 'mB COLUMBIA PLANOGRAPH 1:13., WASHINCI'I'DN, D. C.

ANNE JACOBUS MATHIJS AUGUST BIDDER VAN DER DOES DE BUE. FURNACE.

- APPLICATION FILED was s, 1918. Patented Aug. 26,1919.

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1:?0 y 7 19 L \f/O I llvvglvro i' in snares PATE OFFICE ANNE JACOBUS MATI'IIJS AUGUST BIDDER VAN DER DOES DE BIJE, OF THE HAGUE,

NETHERLANDS.

FURNACE.

Application filed June 6, 1918.

To all whom it may concern:

Be it known that I, ANNE Jaoonns Marlins AUGUST BIDDER van our. DOES on BIJE, gentleman, subject of the Queen of the Netherlands, and resident .of The Hague, Nassau Zuilensteinstraat- 3, the Netherlands, have invented certain new and useful Improvements in Furnaces, of which the following is a specification.

The present invention relates to furnaces, and particularly to boiler furnaces, the ob ject of my invention being to provide a furnace of such improved construction that a more complete fuel combustion is secured.

In the accompanying drawings Figure l is a plan view of the fire bottom according to the invention. Parts of the surrounding boiler have not been shown as not being essential;

Fig. 2 is a section on the line A-A of Fig. 1, showing also some parts of a Yarrowboiler;

Fig. 3 is a section on the line Bl3 of Fig. 1; and

Fig 4 is a section on the line C-C of Fig. 1.

As here shown the grate comprises a longitudinally extending raised mid portion flanked on each side by a depressed portion or gutter. The raised mid portion of the grate has a bar section 6 occupying about one-tenth of the entire grate area and spaced from the furnace mouth or feed hole by a dead grate area 7 formed by a blank feed plate, and followed at its discharge end by a grate area 8 of low draft permeability. The grate area 8 is formed by a perforated plate. The blast openings on the bar area 6 comprise approximately 30% of the total area of the bar section, while the draft openings in the plate 8 comprise but 3% of its area, or approximately one-tenth as great as the blast area through the bar area 6, a large portion being left unperforateiil, while the holes themselves are so spaced and of such size as to prevent the formation of craters in the ash at the discharge end of the fire bed. The three sections 6, 7 and 8 which form the raised mid portion of the grate constitute the firing area proper of the grate.

The depressed portions or gutters on opposite sides of the firing area are connected to the latter by inclined side plates 10 provided with cooling ribs 9 on their lower faces. These plates are perforated toward Specification of Letters Patent.

Patented Aug. 26, 1919.

Serial No. 238,590. 7

their lower edges, as are also the plates which form the bottoms of the depressed marginal areas of the grate, but the perforations in these side and bottom plates are of such size and are so spaced as to constitute but approximately 5% of the total marginal grate area lying on opposite sides of the tiring area proper.

Holes 11 at the rear ends of the depressed side portions of the grate lead to an ash pit and are closed by gates 12 mounted on shafts J3 operated by handles ll to permit the discharge of the ash from the grate.

The -furnace arch 15 has embedded therein blast pipes 16 with flat nozzles opening therefrom to the combustion area above the lire bed, and preferably so shaped as to spread the blast. These nozzles are arranged at predetermined points around the lire chamber to insure an evenly distributed supply of air thereto to support combustion of the gases rising from the fire bed. The air supply passing through the grate and fire bed is preferably about 55 to of the total blast, the remaining 40 to 45% being introduced (preferably preheated) through the pipes 16 to the combustion chamber above the fire bed, thus insuring complete combustion of the furnace gases and consequently a smokeless fire.

The coal is fed forward from the hopper 20 by a pusher 19, which works in the bottom of the hopper and sweeps over the firing area 7 of the grate. Its forward stroke not only pushes in fresh coal but advances the fire bed and thus the ash toward the discharge end of the grate, Its position is such that the fresh coal is shoved into the lower portion of the fire bed below the area of combustion and thus forms a type of underfeed. The advance of the fire bed thus effected by the pusher 19 carries the ash to the discharge end of the grate, where it drops through the holes 11 to the ash pit. If desired supplemental pushers (not shown) may be provided to advance the fuel bed in the marginal portions of the grate.

Various modifications will readily occur to those skilled in the art which do not depart from what I claim as my invention- I claim 1. A furnace grate having a raised longitudinally extending mid portion. depressed draft capacity and the area to the rear thereof having a much lower draft capacity, an underfeed device adapted to advance the fire bed on the central portion of the grate and thus sweep the same, together with means for supplying supplementary air to the combustion chamber above the fire bed.

2. A furnace grate having a raised l0ngitudinallyextending mid portion, depressed portions on opposite sides thereof, the mid area of said raised portion having a large draft capacity and the area to the rear thereof having a draft capacity approximately one-tenth as great, an underfeed device adapted to advance the fire bed on the central portion of the grate and thus sweep the same, together with means for supplying supplementary air to the combustion chamber above thefire bed.

3. A furnace grate having a raised longitudinally extending mid portion, depressed portions on opposite sides thereof, the mid area of said raised portionhaving a large draftcapacity and the area to the rear thereof having a much lower draft capacity, an underfeed device adapted to advance the fire bed on the central portion of the grate and thus sweep the same, together with means for supplying supplemental air to the combustion chamber above the fire the rear end of the marginal areas of the grate for discharging ash therefrom, together with means for advancing fresh fuel to the grate over said dead area and below the combustion zone of the fuel bed, substantially as described.

In testimony whereof I affix my signature.

ANNE JAOOBUS MATHIJS AUGUST BIDDER VAN DER DOES DE BIJE.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents. Washington, D. 0. 

